Allegheny County District Attorney Stephen Zappala said during a Wednesday afternoon news conference that his office continues to investigate the incident and has not yet filed any charges. Although he did say the mother of the boy will not be charged.

"I haven't found anything that would indicate that any crimes were committed by the mother," he told reporters.

Zappala said his office, along the Department of Agriculture and the Association of Zoos and Aquariums, is still investigating whether any charges will be filed against the zoo, and what changes need to be made.

"When these types of things happen, you are talking about responses that are (snaps fingers). I mean, you gotta get in there, and you're talking seconds count, and it took longer than it should to access the facility," he said.

Investigators said Maddox Derkosh's mother picked him up and put him on top of a railing at the edge of a viewing deck on Nov. 4 when he lost his balance and fell into the African painted dogs exhibit.

Zoo President Dr. Barbara Baker said there was a safety net below the railing, but it failed to catch the child, and he dropped more than 10 feet into the enclosure.

Zappala said the boy’s mother attempted to go after him, but she was restrained by others at the exhibit. He said once the boy fell in, he was killed by the dogs in a matter of seconds, and nothing could have been done to save him.

The Allegheny County Medical Examiner's Office said the boy died of blood loss from trauma caused by the dogs.

The attack was so violent and quick that by the time a veterinarian and other zoo staffers arrived seconds later, they determined it would have been futile to try a rescue, Baker said.

Zookeepers called off some of the dogs after the boy fell in the exhibit, and seven of them immediately went to a back building. Three more eventually were drawn away from the child, but the last dog was aggressive and police said they had to shoot it.

Baker said zoo staffers fired blank darts at the dogs instead of actual tranquilizers because they would also be harmful to humans.

The painted dogs are about as big as medium-sized domestic dogs, and weigh 37 to 80 pounds, according to the zoo. They have large, rounded ears and dark brown circles around their eyes and are considered endangered.